In a bowl, combine the ingredients with your fingers. Adjust the cinnamon to your liking.
Preheat the oven to 350 degrees F. Line three loaf pans with baking papers. Set aside.
In a large mixing bowl of a stand mixer or use an electric hand mixer, cream together the butter and sugar.
Add the salt, eggs, vanilla, and sour cream and combine. Occasionally scrape the sides and bottom of the bowl with a rubber spatula.
Add the half of the flour and combine. Scrape the bowl again with a rubber spatula. Add the remaining flour and baking powder and mix until combined.
Fold in the blueberries and peach pieces.
Divide the batter evenly between the three loaf pans. Sprinkle the streusel topping evenly on the top of each unbaked coffee cake. (keep any leftover streusel topping in a freezer safe Ziploc bag)
Place the loaf pans on a half sheet pan lined with parchment paper. Bake in a preheated 350 degree F oven for 60-65 minutes. Cakes are done when a toothpick inserted into the center of the cakes comes out clean.